The invention relates to a pipette.
Pipettes are devices for metering and transferring liquids. They frequently are configured as repeat pipettes or multi-pipettes which allow to dispense a liquid from a syringe in a stepwise manner. A repeat pipette of this type has been known from DE 29 26 691 C2, which is specifically directed to the repeat mechanism of the repeat pipette. The document also describes how to fix a syringe of the system to the repeat pipettes. For this purpose, the syringe has a syringe flange which is adapted to be introduced from a side into a groove which is open laterally and substantially is U-shaped. The syringe flange inserted is fixed in the groove by an axial pressure spring. An insertion element is provided to join the syringe piston to a piston adjusting device and accommodates an end portion of the syringe piston between two jaws. The jaws are designed to be pressed against the syringe piston by means of a flap-shaped clamping member the actuation lever of which protrudes from the casing through an opening. This syringe fixation has the drawback that the syringe needs to be seized in order to insert and couple it to the piston adjusting device and uncouple and remove it therefrom.
DE 43 41 229 C2 proposes a pipette system which is suited better for manual actuation and has a syringe which simply may be pushed into the pipette and removed therefrom axially. This pipette has a syringe exhibiting a mounting portion and a syringe piston, and a pipette which has a seat for the mounting portion in a pipette casing and an accommodating body with a piston seat for the syringe piston. Further, there are mounting devices for reversibly fixing the mounting portion and syringe piston in the seats and piston adjusting devices for the displacement of the accommodating body within the pipette casing. The mounting portion and the syringe piston can be axially pushed into their mounting positions through axial apertures of their seats. The mounting devices have radially advanceable gripping devices for fixing the mounting portion and syringe piston in the mounting positions. The gripping devices have syringe gripping levers pivotally supported within the pipette casing and piston gripping levers pivotally supported within the accommodating body. The syringe gripping levers and piston gripping levers are configured to have two arms including a gripper arm and an actuator arm where the syringe gripping levers, at the insides of their actuator arms, have contact points which when their actuator arms are actuated are adapted to be externally pivoted against the actuator arms of the piston gripping levers and actuate the piston gripping levers. The effect achieved is that the syringe and pipette can be connected to each other by a purely axial relative movement and can be disconnected from each other by an actuation of the mounting devices.
According to an embodiment, a user wanting to disconnect the syringe from the pipette is required to press the actuator arms of two syringe gripping levers inwardly. As a result, the gripping arms let the syringe flange go while the unlocking cams of the syringe gripping levers exert a force on the actuator arms of the syringe gripping levers so that those let the syringe piston go. Pre-loaded spiral-coiled springs of a flange stop apply a pressure towards the axial aperture of the repeat pipette to eject the syringe. For a separation of the syringe from the pipette, it is necessary to actuate the two syringe gripping levers by two fingers simultaneously.
Accordingly, it is the object of the invention to provide a pipette in which the syringe can be released from the pipette by an actuation of only a single trigger.